Electrolytic cell



ELECTROLYTIC CELL Filed July 5, 1926 ,mw-m U /mw Patented Mar. 31, 1931UNITED STATES PATENT ori-ICE y HERBERT I. ALLEN .AND :DOUGLAS B. AYERST,OF PORTLAAND, MAINE, ASSIGNOBS TO ELECTRON CHEMICAL CQMPANY, F PORTLAND,MAINE, A CORPVORATION' 0F ELEoTRoLYTIo CELL Application led July 3,1926. Serial No. 120,421.

This invention relates to electrolytic cells, more particularly to theso-called non-submerged cathode and diaphragm type such as are used forthe decomposition of brine in the formation of caustic soda. I

One of the objects of this invention is to increase the eiciency andcapacity of the cell. By increasing the capacity, less ioor space isrequired for the same output, thus decreas- 1o ing the costoconstruction of the building for housing the cells and of the cellequipment for a given capacity.

The increase in eiciency and output capacity of the cell is produced toa large extent by so forming the cell that an increased proportion oftotal anode area is rendered eii'ective, and by so forming the anodethat flow of current is facilitated.

To provide increased active-anode area,

the cathode, formed as abox of foraminous metal such as iron, is soshaped as to present afplaitedsurface between adjacent stretches o whichthe anodes are positioned. Thus each anode has positioned portions ofthe cathode closely adjacentthereto Von opposite sides so that bothsides of the anode are active, and the plaiting of the cathode permits alarger active proportion of total anode area to be used for each cell. vTo increase the effectiveness of the anodes to a further extent, theyare so formed as to present a considerably increased length of edgeportions.

For a more complete understanding of this invention, reference may behad to the accompanying drawings in which F11gure 1 1s a somewhatdiagrammatic view part y in side elevation and partly in verticalsection through a cell embodying this invention. f Figure2isatop planview. Figure 3 is a transverse vertical section on line 3-3 of Figure 1.Fi re 4 is a diagrammatic view illustratt e manner of cutting a pair ofanodes. gure 5 is a perspective of the cathode baske A F Figure 6 is adetail section on line 6 6 of eferring to these drawings, at 1- isopposite sides 12 and a reentrant loo shown more particularly in Fidicated a tank of suitable construction suchas iron and having an"inturned marginal flange 2 on its upper edge on which is supported thefreeboard section 3. This freeboard section is preferably formed ofconcrete and is clamped to the tank by any suitable means, such, forexample, as the tie bolts 4, having looped lower extremities engagingabout hooks 5 extending from the outer face of the tank and having theirupper ends threaded and extended through bars 6' resting on the upperface of the freeboard section, nuts 7' being shown as threaded on theupper ends of the tie bolts above the bars.

Interposed between the tank and the freeboard section at the joint arethe out-turned v flanges 8 ofthe cathode which are overlaid by the upper`ends of a porous diaphragm 9 of asbestos paper or like material', theflange 8 and the dia hra being so clamped between the free oar sectionand the tank as to produce a liquid and gas tight joint therebetween.

As shown more particularly in Figure 5, the cathode 10 comprises aforaminous plate 11 bent into vertically plaited form having portion 13.Bridging the edges of the p ate 11 are end lates 14, which are fixed tothe edges of the p ate 11, as by spot welding at intervals so as toproduce a general box shaped foraminous tank having two compartments 15separated from each other by the upwardly looped portion 13 formed bythe plaiting of the sheet. The interior of each of these' cclmpartmentlsis lirpd vvithlalnl abeltos diap ragm over ying-t ep ate an t eu r edgesof the diaphra beingmclampetbatween the cathode an the free ard sectionsas previously described. The sides, ends and bottom are eachelectrically active. v

Within each of the compartments 1 5,- which contain electrolyte, are snded anodes 20, there being two series o anodes as s 1 .and 91s 3. Eachof the anodes comprises a lower substantially rectangular portion 21having vintegrally therewith andl eccentricall or otherwise disposedrelative thereto a le member 22- which extends through the free- 10otor.

board section and through openings 23 suitably spaced through the cover19 which may if desired be formed of concrete similar to the side andend walls of the freeboard section.-

By forming the leads 22 eccentric to the longitudinal axis of portion 21the'anodes can be cut from .plates of graphite or other suitablematerial in a manner shown in Figure 4, the plates being of combinedwidths no greater than the width of the` portions 21 and 22. By thismeans there is little waste in cutting the anodes from the material.'The upper edge of the rectangular portion 21 is positioned slightlybelow the joint between the tank and freeboard section in order thatduring the normal operation of the cell the level of the electrolyte isabove it. This permits circulation of the electrolyte beneath the loweredge of each anode and over the upper edge adjacent to the lead member22. As shown, oppositely positioned anodes extending into the twocompartments 15 are fixed together in suitably spaced relation byspacing elements 25, each having reduced extremities extending intoperforations in the lead members as at 26 and a central enlarged portion27 which acts to space the anodes apart. The anodes are supported fromopposite side walls of the freeboard section by means of pins 28extending through each anode of each opposed pair and resting insuitable recesses 29 in the inner face of the freeboard wall 3. Theseanode lead portions extend through the openings 23 of the cover and areconnected to a bus bar 30 extending'along the top of the cell as bymeans of the conductors 24. It will be noted that the pins 28 passeccentrically through the anode lead portions, this being for thepurpose of permitting a proper balance of the anodes so that they tendto take a substantially vertical position, the pins 28 passing throughthe anodes substantially above their gravity axes when they arevertical.

To further facilitate the passage of current from the anodes they arepreferably formed to present a multiplicity of corners, it being wellknown that an edge or a point facilitates the discharge of current froma conduc- For this purpose the body portions 21 of the anodes-are shownas cut upwardly as by means of a saw to form a series of closely spacedkerfs 35 to divide the major portion of the active anode into a seriesof relatively narrow bars 36 as shown more particularly in Figure 6. Inoperation the edges 37 defined by the kerfs 35 are subject to activecurrent emission and gradually become wasted away so that the portions36 take a general oval form as shown in the dotted` lines at 38 inFigure 6. These oval portions however are still more eliicient inpermitting the discharge of current than a flat plate would be. Whileanodes might be made in small slabs to obtain an extensive edge len h,this would require fabrication and woul be more expensive than forminkerfs in anodes of substantial size. At 40 1s shown a gas escape and at41 is shown a supply pipe through which brine may be passe The centralcompartment formed Within the looped portion 15 and the sidecompartments between the compartments 15 and the tank- 1 are free fromelectrolyte, but receive the eiiluent from the anode compartments andthe gas liberated at the cathode. The eiiluent may be led off from thecell after passing throu h the A diaphragm and the cathode throug thepipe 42..

Particularly when this cell is used for electrolysis of brine to formcaustic soda, hydrogen and chlorine, the top of the central compartmentformed between the sides of the central plait and looped portion 13 andcovered by the diaphragm should be below the out-turned cathode flanges8, as shown in Figure 3, so that the hydrogen accumulating in thecentral compartment may flow freely through the foraminous end wallsthereof and be taken olfv from the cell outwardly of the cathode. Thusthe cathode compartment in which the hydrogen accumulates has itshighest part along the exterior wa-ll in direct communication with theexit (not shown) always provided at the top of the tank just below thecathode flanges in cells of the freeboard type. Hydrogen being a verylight, tenuous gas, is diiicult to confine and handle and if, -forexample, the top of the central cathode compartment formed by theplating of the cathode were higher than the side compartments, hydrogenwould tend to accumulate from the outer compartment in this innercompartment and exert an upward pressure, which would result in hydrogenpassing through the diaphragm and through the superimposed electrolyteinto the anode chamber where it might mix in explosive proportions withthe chlorine. The increased hydrostatic head over the top of the middlecathode compartment also aids to prevent the escape of hydrogen into thefreeboard section. Moreover, it is exceedingly important inasmuch assubstantially-half of the hydrogen producedby the cell is collected inthis central compartment that there be absolutely free communicationbetween this central cathode compartment and the two outer c athodecompartments to prevent the trapping of hydrogen. It is also importantthat the central compartment between the anode compartments be open atits lower end or bottom so as to permit free escape therefrom of theeiiiuent from the anode compartments. 'lhis prevents the return of theeffluent to the anode compartments which would contaminate theelectrolyte and cause side reactions with resultant loss in celleiiiciency, im-

d mto the cell.

purity of reaction products, and shortened life of the anodes.

Whi-le as shown the cathode is plaited to, provide a pair ofcompartments 15 which areV they might be positioned laterally ratherthan longitudinally of the cell. Current connections may be made to thecathode by any suitable means, but as shown in Figure 5 a portion of oneof the flanges 8, has been extended as at 43, its outer end beingupwardly turned as at 44 and fixedV to the bus bar 45.

An embodiment of this invention having thus been described, it should beevident to those skilled in the art that many other changes andmodifications might be lmade therein without departing from the spiritor scope ofthe invention as defined by the appended claims.

We claim:

1./An electrolytic cell comprising a tank, a cathode comprising aforaminous sheet formed vertically in plaits and having end flangesresting on the walls of said tank, plates of foraminous materialbridging the ends of said plaits and.iixed thereto, a free'- boardsection supported on said tank, and rows of anodes supported by saidfreeboard section and depending between the plaits of said sheet, saidplaits forming a chamber between said anodes open at its bottom.

2. In a divice of the class described, a cathode comprising a box havingelectrically active foraminous sides, ends, and bottom, said sides andends forming a substantially rectangular frame, andI said bottom beingplaited to form with said sides and ends a plurality of compartmentsopen alternately at top and bottom, the edges ofsaid bottoni betweensaid sides being fixed to the inner.

faces of said ends.

3. In a device of the class described, a cathode comprising a box havingelectrically active foraminous sides, ends, and bottom, each of saidends being rectangular and said sides and bottom being formed of asingle sheet plaited to form with said ends a plurality of compartmentsopen alternately at top and bottom, theedges of said sheet .engaging andbeing fixed to the inner faces of said ends, and an anode betweenadjacent faces of each plait in each of said compartments open at itstop, said anodes being in operative relation to said sides, ends andcathode bottom.

4. In a device ofthe class described, a cathode .comprising electricallyactive foraminous sides, ends and a bottom, said bottom' being plaitedand having its edges secured to the inner faces of said ends and formingwith said ends and sides a plurality .of cornpartments open alternatelyat top and bottoni.

5. In a device of the class described, a cathode comprising "a boxhaving electrically active fo'raminous sides", ends and bottom, saidbottom being plaited to forni with said sides and ends aj pair of sidecompartments having open tops and a central compartment having a closedtop, said central compartment being open through said ends for the freepassage of gaseous products of electrolysis.

6. In a de vicey ofthe Vclass described, a cathode comprising aboxhaving electrically active foraminous sides, ends and bottom, saidbottom being plaited to form with said sides and ends avpair of sidecompartments having open tops and a'central compartment having a closedtop, said central compartment having `perforations distributed oversubstantially'its entire end areas for the free passage of gaseousproducts of electrolysis.

7. A device of the class described comprising a container,a cathodesuspended in said container and comprising two spaced apart parallelelectrolyte containing chambers, a diaphragm lining each chamber, thefour sides and bottom of each chamber being active, a chamber free'fromelectrolyte located between the electrolyte chambers, and anodesextending into said electrolyte chambers, said 'chamber free fromelectrolyte having end openings for the free escape ofvgaseous productsof electrolysis therefrom.

' 8. An electrolytic cell comprising a container, a` cathode suspendedtherein, said cathode comprising two spaced apart elec'-trolyte-containing chambers, anodes in said electrolyte-containingchambers, said la'st mentioned chambers being closed at their tops, thetop end of said chamber between said electrolyte-containing chambersbein below the tops of said outwardly positione chainbers, and saidchambers free from electrolyte being in free communication with eachother for the passagev of roducts of'electrolysis.

9.`In a device '0F the class described, a cathode comprisng a box havingelectrically active foraminous sides, ends and bottom, said sides andends forming a substantially rectangular frame, said bottom beingplaited to form with said sides and ends a pair of anode compartmentsfor the reception of electrolyte spaced by a compartment free fromelectrol te, said bottom being fixed to said end wa ls which providefree exit from said spacing compartment through the openings in said endwalls for the products of eleciao ` ..tiYee-:foraminous si'des, ends andbottom,

said sides and ends forming a substantially rectangular frame, saidbottom being plaited to form with said sides and ends a pair of 5 anodecompartment-s for the reception of electrolyte spaced by a compartmentfree from electrolyte, said bottom being xed to said end wallsWhich'provide free exit from said spacing compartment through theopenings in said end Walls for the products of'electrolysis enteringsaid spacing compartment, and a diaphragm lining saidanode-compartment-s, and extending over said spacing compartment, saidspacing compartment having an open bottom and its top being below thetop of said cathode. Y

In testimony whereof we have aiiixed ou signatures.

HERBERT I. ALLEN. DOUGLAS B. AYERST.

